lint: [move-only] Move docs related lints to lint_docs.rs

diff --git a/test/lint/test_runner/src/lint_docs.rs b/test/lint/test_runner/src/lint_docs.rs
new file mode 100644
index 00000000..7063b508
--- /dev/null
+++ b/test/lint/test_runner/src/lint_docs.rs
@@ -0,0 +1,85 @@
+// Copyright (c) The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or https://opensource.org/license/mit/.
+
+use std::io::ErrorKind;
+use std::process::{Command, Stdio};
+
+use crate::util::{check_output, get_subtrees, git, LintResult};
+
+pub fn lint_doc_release_note_snippets() -> LintResult {
+    let non_release_notes = check_output(git().args([
+        "ls-files",
+        "--",
+        "doc/release-notes/",
+        ":(exclude)doc/release-notes/*.*.md", // Assume that at least one dot implies a proper release note
+    ]))?;
+    if non_release_notes.is_empty() {
+        Ok(())
+    } else {
+        println!("{non_release_notes}");
+        Err(r#"
+Release note snippets and other docs must be put into the doc/ folder directly.
+
+The doc/release-notes/ folder is for archived release notes of previous releases only. Snippets are
+expected to follow the naming "/doc/release-notes-<PR number>.md".
+            "#
+        .trim()
+        .to_string())
+    }
+}
+
+pub fn lint_doc_args() -> LintResult {
+    if Command::new("test/lint/check-doc.py")
+        .status()
+        .expect("command error")
+        .success()
+    {
+        Ok(())
+    } else {
+        Err("".to_string())
+    }
+}
+
+pub fn lint_markdown() -> LintResult {
+    let bin_name = "mlc";
+    let mut md_ignore_paths = get_subtrees();
+    md_ignore_paths.push("./doc/README_doxygen.md");
+    let md_ignore_path_str = md_ignore_paths.join(",");
+
+    let mut cmd = Command::new(bin_name);
+    cmd.args([
+        "--offline",
+        "--ignore-path",
+        md_ignore_path_str.as_str(),
+        "--gitignore",
+        "--gituntracked",
+        "--root-dir",
+        ".",
+    ])
+    .stdout(Stdio::null()); // Suppress overly-verbose output
+
+    match cmd.output() {
+        Ok(output) if output.status.success() => Ok(()),
+        Ok(output) => {
+            let stderr = String::from_utf8_lossy(&output.stderr);
+            Err(format!(
+                r#"
+One or more markdown links are broken.
+
+Note: relative links are preferred as jump-to-file works natively within Emacs, but they are not required.
+
+Markdown link errors found:
+{stderr}
+                "#
+            )
+            .trim()
+            .to_string())
+        }
+        Err(e) if e.kind() == ErrorKind::NotFound => {
+            println!("`mlc` was not found in $PATH, skipping markdown lint check.");
+            Ok(())
+        }
+        Err(e) => Err(format!("Error running mlc: {e}")), // Misc errors
+    }
+}
diff --git a/test/lint/test_runner/src/main.rs b/test/lint/test_runner/src/main.rs
index ddcdd178..9adbe369 100644
--- a/test/lint/test_runner/src/main.rs
+++ b/test/lint/test_runner/src/main.rs
@@ -2,14 +2,16 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or https://opensource.org/license/mit/.
 
+mod lint_docs;
 mod lint_text_format;
 mod util;
 
 use std::env;
 use std::fs;
 use std::io::ErrorKind;
-use std::process::{Command, ExitCode, Stdio};
+use std::process::{Command, ExitCode};
 
+use lint_docs::{lint_doc_args, lint_doc_release_note_snippets, lint_markdown};
 use lint_text_format::{
     lint_commit_msg, lint_tabs_whitespace, lint_trailing_newline, lint_trailing_whitespace,
 };
@@ -29,7 +31,7 @@ fn get_linter_list() -> Vec<&'static Linter> {
         &Linter {
             description: "Check that all command line arguments are documented.",
             name: "doc",
-            lint_fn: lint_doc
+            lint_fn: lint_doc_args
         },
         &Linter {
             description: "Check that no symbol from bitcoin-build-config.h is used without the header being included",
@@ -344,28 +346,6 @@ include of the boost/assert.hpp dependency.
     }
 }
 
-fn lint_doc_release_note_snippets() -> LintResult {
-    let non_release_notes = check_output(git().args([
-        "ls-files",
-        "--",
-        "doc/release-notes/",
-        ":(exclude)doc/release-notes/*.*.md", // Assume that at least one dot implies a proper release note
-    ]))?;
-    if non_release_notes.is_empty() {
-        Ok(())
-    } else {
-        println!("{non_release_notes}");
-        Err(r#"
-Release note snippets and other docs must be put into the doc/ folder directly.
-
-The doc/release-notes/ folder is for archived release notes of previous releases only. Snippets are
-expected to follow the naming "/doc/release-notes-<PR number>.md".
-            "#
-        .trim()
-        .to_string())
-    }
-}
-
 fn lint_includes_build_config() -> LintResult {
     let config_path = "./cmake/bitcoin-build-config.h.in";
     let defines_regex = format!(
@@ -455,61 +435,6 @@ the header. Consider removing the unused include.
     Ok(())
 }
 
-fn lint_doc() -> LintResult {
-    if Command::new("test/lint/check-doc.py")
-        .status()
-        .expect("command error")
-        .success()
-    {
-        Ok(())
-    } else {
-        Err("".to_string())
-    }
-}
-
-fn lint_markdown() -> LintResult {
-    let bin_name = "mlc";
-    let mut md_ignore_paths = get_subtrees();
-    md_ignore_paths.push("./doc/README_doxygen.md");
-    let md_ignore_path_str = md_ignore_paths.join(",");
-
-    let mut cmd = Command::new(bin_name);
-    cmd.args([
-        "--offline",
-        "--ignore-path",
-        md_ignore_path_str.as_str(),
-        "--gitignore",
-        "--gituntracked",
-        "--root-dir",
-        ".",
-    ])
-    .stdout(Stdio::null()); // Suppress overly-verbose output
-
-    match cmd.output() {
-        Ok(output) if output.status.success() => Ok(()),
-        Ok(output) => {
-            let stderr = String::from_utf8_lossy(&output.stderr);
-            Err(format!(
-                r#"
-One or more markdown links are broken.
-
-Note: relative links are preferred as jump-to-file works natively within Emacs, but they are not required.
-
-Markdown link errors found:
-{stderr}
-                "#
-            )
-            .trim()
-            .to_string())
-        }
-        Err(e) if e.kind() == ErrorKind::NotFound => {
-            println!("`mlc` was not found in $PATH, skipping markdown lint check.");
-            Ok(())
-        }
-        Err(e) => Err(format!("Error running mlc: {e}")), // Misc errors
-    }
-}
-
 fn run_all_python_linters() -> LintResult {
     let mut good = true;
     let lint_dir = get_git_root().join("test/lint");